BGE - How do I make an sound stop when pressing a key, then start again when releasing it?
You need to have the logic in place to disable the original sound.



Rather than using an always sensor to activate the normal sound,use a Nand or Nor controller attached to the original keypress that plays the second sound. If this still doesn't work, activate TRUE and False level triggering which will make the sensor activate (and deactivate, respectively).

These are the two little buttons, each containing 3 dots, on the sensor.